How to unlock: Speak with director Tann [Nexus: Operations Center].
Here you can find the walkthrough for Missing Arks quest. This is one of the side quests in Mass Effect: Andromeda game that belongs to the category called "Allies and relationships". In this quest you must find traces of the three titular Arks that didn't arrive at Nexus - these Arks belongs to Turians, Salarians and Asari.
This quest should be automatically added to your journal during the first meeting with director Tann in Nexus: Operations Center which happens during A Better Beginning main quest. You learn about the missing Arks belonging to other races. You can talk to Tann again in order to get more information about this topic. You agree to find them.
You can't continue this quest right after you receive it. It becomes suspended and automatically updated in the later parts of the game when you find the tracks of the missing Arks (the next tracks can be investigated during other quests):
- Turian Ark - You can find its tracks during your exploration of planet Havarl. You can come across Turians that defends themselves and you unlock Turian Ark: Not Dead Yet side quest. After making enough progress in the main storyline you can start the next quest connected with that Ark - Turian Ark: Lost but Not Forgotten.
- Salarian Ark - You won't miss this Ark because it's the part of other main quest called Hunting the Archon. The Ark is in the place where you find the Kett Flagship. The isnside of said Ark is explored during that quest.
- Asari Ark - You can find its tracks during a side quest called Cora Harper: Asari Ark in which you must explore planet Voeld. The Ark itself is found during Cora's Loyalty Mission - Cora Harper: At Duty's Edge.
Rewards for finishing the quest: XP.